Gate-all-around fin device

ABSTRACT

A gate-all around fin double diffused metal oxide semiconductor (DMOS) devices and methods of manufacture are disclosed. The method includes forming a plurality of fin structures from a substrate. The method further includes forming a well of a first conductivity type and a second conductivity type within the substrate and corresponding fin structures of the plurality of fin structures. The method further includes forming a source contact on an exposed portion of a first fin structure. The method further comprises forming drain contacts on exposed portions of adjacent fin structures to the first fin structure. The method further includes forming a gate structure in a dielectric fill material about the first fin structure and extending over the well of the first conductivity type.

FIELD OF THE INVENTION

The invention relates to semiconductor structures and, moreparticularly, to gate-all around fin double diffused metal oxidesemiconductor (DMOS) devices and methods of manufacture.

BACKGROUND

Integrated circuit (semiconductor) devices, e.g., field effecttransistors (FETs), are used in logic, memory, processor, communicationdevices, e.g., microwave communication, and other integrated circuitdevices. The PET includes spaced apart source and drain regions, achannel there between and a gate electrode adjacent the channel. As theintegration density of integrated circuit FETs continues to increase,the size of the active region and the channel length decreases.

FinFET technologies have been developed to increase chip density, whileallowing a further scaling of the channel length. Although the FinFETtechnologies can deliver superior levels of scalability, designengineers still face significant challenges in creating designs thatoptimize the FinFET technologies. For example, as process technologiescontinue to shrink towards 14-nanometers (nm), it is becoming difficultto achieve a similar scaling of certain device parameters, particularlythe power supply voltage, which is the dominant factor in determiningdynamic power. For example, design engineers still face significantchallenges to design higher voltage FET devices which can handle >2V infin based technologies for 14 nm and beyond.

SUMMARY

In an aspect of the invention, a method comprises forming a plurality offin structures from a substrate. The method further comprises forming awell of a first conductivity type and a second conductivity type withinthe substrate and corresponding fin structures of the plurality of finstructures. The method further comprises forming a source contact on anexposed portion of a first fin structure. The method further comprisesforming drain contacts on exposed portions of adjacent fin structures tothe first fin structure. The method further comprises forming a gatestructure in a dielectric fill material about the first fin structureand extending over the well of the first conductivity type.

In an aspect of the invention, a method comprises: forming a pluralityof fin structures from a substrate; implanting a first conductivity typein the substrate to form an N-well and n-implanted fin structures of theplurality of fin structures; implanting a second conductivity type inthe substrate to form a P-well and p-implanted fin structures of theplurality of fin structures; forming a source contact on an exposedportion of one p-implanted fin structure; forming drain contacts onexposed portions of adjacent fin structures to the p-implanted finstructure; and forming a gate about the p-implanted fin structurecomprising the source contact and extending over the N-well.

In an aspect of the invention, a diffused metal oxide semiconductor(DMOS) device comprises: a substrate of a first conductivity type; adoped well located in the substrate of the first conductivity type; adoped well ring of a second conductivity type and enclosing a centralwell of the first conductivity type; a first doped fin contact region ofthe first conductivity type forming a source contact to a gate structureover the central well of the first conductivity type; a second doped fincontact region of the second conductivity type forming drain regions tothe gate structure, the second doped fin contact region being formed inthe over the doped well ring; and the gate structure over an insulatinglayer above the central well configured vertically around a fin regionof the first doped fin contact region and laterally extending in thedirection of and crossing over onto the doped well ring.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The present invention is described in the detailed description whichfollows, in reference to the noted plurality of drawings by way ofnon-limiting examples of exemplary embodiments of the present invention.

FIGS. 1-5B show structures and respective processing steps in accordancewith an aspect of the present invention; and

FIGS. 6-12 show additional structures and respective fabricationprocesses in accordance with additional aspects of the presentinvention.

DETAILED DESCRIPTION

The invention relates to semiconductor structures and, moreparticularly, to gate-all around fin double diffused metal oxidesemiconductor (DMOS) devices and methods of manufacture. Advantageously,the different structures of the present invention each enable >2V MOSFETcapability in 14 nm bulk substrates and beyond.

In embodiments, the diffused metal oxide semiconductor (DMOS) device arefully depleted, vertical gate all around controlled, high voltagefin-based metal oxide semiconductor (MOS) devices. In embodiments, thedevices comprise several different configurations as described herein.For example, in one configuration, the MOS device comprises: a substrateof the first electrical conductivity type; a lightly doped well locatedin the substrate of the first electrical conductivity type; a secondlightly doped well ring of the second electrical conductivity typelocated in the first well and enclosing a third central well of thefirst well type; a first highly doped fin contact region of the firstelectrical conductivity type in the first electrical conductivity type;a second highly doped fin contact region of the second electrical typein the second lightly doped well ring; a third highly doped fin contactregion of alternating first and second electrical conductivity type inthe third central well; and a field plate (gate structure) over aninsulating layer above the central well configured vertically around thefin region and laterally extending in the direction of, and crossingover, onto the second well.

The structures of the present invention can be manufactured in a numberof ways using a number of different tools. In general, though, themethodologies and tools are used to form structures with dimensions inthe micrometer and nanometer scale. The methodologies, i.e.,technologies, employed to manufacture the structures of the presentinvention have been adopted from integrated circuit (IC) technology. Forexample, the structures of the present invention are built on wafers andare realized in films of material patterned by photolithographicprocesses on the top of a wafer. In particular, the fabrication of thestructures of the present invention uses three basic building blocks:(i) deposition of thin films of material on a substrate, (ii) applying apatterned mask on top of the films by photolithographic imaging, and(iii) etching the films selectively to the mask.

FIG. 1 shows a starting structure in accordance with aspects of thepresent invention. In particular, the structure 10 comprises a bulksubstrate 12 with a plurality of fins 14. In embodiments, the substrate12 may be composed of any suitable material including, but not limitedto, Si, SiGe, SiGeC, SiC, GE alloys, GaAs, InAs, InP, and other III/V orII/VI compound semiconductors. The fins 14 can be manufactured usingknown lithography and etching processes. For example, the fins 14 can bemanufactured using sidewall image transfer (SIT) techniques.

In the SIT technique, for example, a mandrel is formed on the substrate12, using conventional deposition, lithography and etching processes. Inone example, the mandrel material, e.g., SiO₂, is deposited on thesubstrate 12 using conventional CVD processes. A resist is formed on themandrel material, and exposed to light to form a pattern (openings). Areactive ion etching is performed through the openings to form themandrels. In embodiments, the mandrels can have different widths and/orspacing depending on the desired dimensions between the narrow finstructures and/or wide fin structures. (A SIT squared technique can beused to form different spacings between adjacent narrow fin structures.)Spacers are formed on the sidewalls of the mandrels which are preferablymaterial that is different than the mandrels, and which are formed usingconventional deposition processes known to those of skill in the art.The spacers can have a width which matches the dimensions of the finstructures 14, for example. The mandrels are removed or stripped using aconventional etching process, selective to the mandrel material. Anetching is then performed within the spacing of the spacers to form thesub-lithographic features. The sidewall spacers can then be stripped. Inembodiments, the wide fin structures can also be formed during this orother patterning processes, or through other conventional patterningprocesses, as contemplated by the present invention. The fins 14 canhave any height L0, depending upon the constraints of the fabricationprocess.

In FIG. 2, shallow trench isolation (STI) structures 16 are formed inthe substrate 12, between the fins 14 and 14′. The STI structures 16 canbe formed using conventional lithography, etching and depositionprocesses. For example, a resist can be formed on the substrate 12 andover the fins 14 and 14′, and patterned by exposure to energy (light).The patterning will result in openings which provide a window foretching processes, e.g., removal of exposed substrate 12. Inembodiments, the etching can be a reactive ion etching (RIE) used withthe appropriate etchant chemistries to form trenches in the substrate12. After the etching process, any remaining resist material can beremoved by an oxygen ashing process or other stripping processes knownto those of skill in the art. An insulator material can be deposited onthe substrate 12, resulting in the STI structures 16 and a dielectricfill 18 between all of the fins.

In FIG. 3, the structure undergoes N-well and P-well implantationprocesses using separate masking and implantation processes. The N-wells20 can be a lightly doped ring structure, which encloses a conductivityof a different type, e.g., P-well. The N-wells 20 will be drift regions,bringing the current from a source region to a drain region. Also, theN-wells 20 can be modulated for larger or smaller voltage drops(depending on design criteria) by adjusting the distance between thefins 14 and 14′. The N-wells 20 will also be spaced away from the centerfin 14 by a distance L2, which will account for the parasitic gatelength. In embodiments, it is preferably to minimize the parasitic gatelength, L2.

Prior to forming the N-wells 20 and the P-wells 22, a deep blanket boronimplant is formed, which is used to assure full depletion of the driftregions in the N-well when the device is in the off state. This deepp-band implant is shown at reference numeral 13. The p-band implant canbe a boron implant at approximately 4e12 to 9e12 cm-3 at 65 to 130 keV.

To form the N-wells 20, a mask is placed over the substrate 12 andpatterned to form openings corresponding to the N-wells. Thereafter, anN-well implantation is performed to form the N-wells 20. In embodiments,the N-well implantation can be a phosphorous implantation process, knownto those of skill in the art. For example, the phosphorous implantationprocess can comprise two implant processes, e.g., one deep and oneshallow to optimize competing device characteristics. For example, thephosphorous implantation process can include a first implantation atapproximately 3e12 to 4e13 cm-3 at 15 to 350 keV and a secondimplantation at approximately 1e12 to 8e12 cm-3 at 10 to 200 keV, inorder to form a deep N-well implant region 20. This process will resultin the fins 14′ having an N-implantation. After implantation processesare complete, the mask can be removed using known stripants or removalprocesses.

On the other hand, the P-wells 22 are formed with a separate mask placedover the substrate and patterned to form openings corresponding to theP-wells. After the patterning, e.g., forming of openings, a P-wellimplantation is performed to form the P-wells 22. In embodiments, theP-well implantation can be a boron implantation process, known to thoseof skill in the art. For example, a boron implantation process cancomprise two implant processes, e.g., one deep and one shallow tooptimize competing device characteristics. For example, the boronimplantation process can include a first implantation of approximately9e12 to 4e13 cm-3 at 20 to 80 keV and a second implantation process ofapproximately 0 to 1e13 cm-3 at 10 to 40 keV, in order to form P-wellimplant regions 22. This process will result in the fins 14 having aP-implantation. After implantation processes are complete, the mask canbe removed using known stripants or removal processes.

Referring now to FIG. 4, epitaxial growth and implantation processes areperformed about exposed portions of the fins 14, 14′, e.g., above thedielectric fill 18. In embodiments, the epitaxial growth process willresult in a semiconductor material being grown about the exposed tips ofthe fins 14, 14′ (e.g., consuming the exposed tips of the fins 14, 14′),followed by an implantation process (highly doped) to form n+ regions 24and p+ regions 24′ (using separate masking steps). As should beunderstood by those of skill in the art, the implantation processes isused to the form source region 25 (corresponding to the center fin 14)and drain regions 25′ (corresponding to the adjacent fins 14′), as wellas p+ body contacts 24′ using the outer fins 14″. Specifically, inembodiments, the fins 14′ and more specifically the highly doped n+region 24 of the fins 14′ will be drain regions 25′; whereas, the highlydoped n+ region 24 of the center fin 14 will be a source region 25.Moreover, the highly doped p+ region 24′ of the fins 14″ are bodycontacts.

Referring to FIGS. 5A and 5B, in additional processing steps a wraparound gate structure 26 is formed about the center fin 14. Inembodiments, the gate structure 26 can be a replacement gate structureprocess, with a gate dielectric material and metal material. Inembodiments, the gate structure 26 extends over the N-wells 20. The gatestructure 26 can be formed by removing portions of the dielectric fillmaterial 18 about the center fin 14, followed by deposition of a highquality low-K gate dielectric and metallic material. The gate structurecan be configured vertically around the fin region and laterallyextending in the direction of and crossing over onto the well regions,as described in the different embodiments herein.

More specifically, the dielectric fill material 18 can be removed usingconventional lithography and etching processes. After removal of anyresist used in the lithography process, the gate dielectric material canthen be deposited on the substrate 12 and about sidewalls of the centerfin 14. The gate dielectric material can be a high-k dielectricmaterial, e.g., hafnium based material. A metal or combination of metalssuch as tungsten fill is then formed (deposited) on the gate dielectricmaterial. The metal material can be combinations of metals with certaindesigned work functions, depending on the design criteria of the gatestructure 26. In embodiments, the dielectric material and the metalmaterial(s) can be deposited using any conventional deposition methodsuch as chemical vapor deposition (CVD), plasma enhanced CVD (PECVD),etc.

FIG. 6 shows another structure and respective fabrication processes inaccordance with additional aspects of the present invention. In thisaspect of the present invention, the structure 10′ includes a continuousdeep N-well region 20′ formed entirely under the center fin 14 and thefins 14′, e.g., source and drain regions 25, 25′. This configurationwill form a floating p-fin 14. The N-well region 20′ can be formed usingthe processes described herein, with a mask of a different openingcorresponding to the N-well region 20′.

FIG. 7 shows another structure and respective fabrication processes inaccordance with additional aspects of the present invention. In thisaspect of the present invention, the structure 10″ includes shallowN-well regions 20″ formed under the fins 14′, e.g., drain regions 25′,and extending partially underneath the gate structure 26. The N-wellregions 20″ can be formed using the processes described herein, with amask of a different opening corresponding to the N-well regions 20″ andan implantation process that will result in a shallow N-well 20″. Forexample, in this process, the implantation process using phosphorous canbe at an energy level of approximately, 1e12 to 1e13 cm-3, 45 to 150keV.

FIG. 8 shows another structure and respective fabrication processes inaccordance with additional aspects of the present invention. In thisaspect of the present invention, the structure 10′″ includes acontinuous shallow N-well region 20′″ formed under the fins 14, 14′,e.g., source and drain regions 25, 25′, and fully underneath the gatestructure 26. This configuration will form a floating p-fin 14. TheN-well region 20′″ can be formed using the processes described herein,with a mask of a different opening corresponding to the N-well region20′″ and an implantation process that will result in a shallow N-wellregion 20′″ as described with reference to FIG. 7.

FIGS. 9-12 show additional structures and respective fabricationprocesses in accordance with additional aspects of the presentinvention. In these representations, the structures (including thestructure 10″″ of FIG. 9) include the p+ body contacts 25″ directly onthe fin 14. In these embodiments, the alternating n+ and p+ regions canbe formed with different masks and implantation processes as discussedherein. In addition, the outer fins (e.g., 14″ shown in FIG. 4) are nolonger required. In these structures, the SIT technique is used to formthe center fin 14 and the fins 14′, for subsequent formation of thesource and drain regions, as represented by reference numerals 25 and25′, respectively. The source and drain regions 25, 25′ are formed usingthe processes as already described herein.

FIG. 10 shows another structure and respective fabrication processes inaccordance with additional aspects of the present invention. In thisaspect of the present invention, the structure 10′″″ includes acontinuous shallow N-well region 20′″ formed under the fins 14, 14′,e.g., source and drain regions 25, 25′, and fully underneath the gatestructure 26. This configuration will form a floating p-fin 14. TheN-well region 20′″ can be formed using the processes described herein,with a mask of a different opening corresponding to the N-well region20′″ and an implantation process that will result in a shallow N-well20′″ as described with reference to FIGS. 7 and 8. The structure 10′″″of FIG. 10 is also devoid of the STI structures 16.

FIG. 11 shows another structure and respective fabrication processes inaccordance with additional aspects of the present invention. In thisaspect of the present invention, the structure 10″″″ includes acontinuous deep N-well region 20′ formed entirely under the center fin14 and the fins 14′, e.g., source and drain regions 25, 25′. Thisconfiguration will form a floating p-fin 14. The N-well region 20′ canbe formed using the processes described herein, with a mask of adifferent opening corresponding to the N-well region 20′.

FIG. 12 shows another structure and respective fabrication processes inaccordance with additional aspects of the present invention. In thisaspect of the present invention, the structure 10′″″″ includes shallowN-well regions 20″ formed under the fins 14′, e.g., drain regions 25′,and partially extending underneath the gate structure 26. The N-wellregions 20″ can be formed using the processes described herein, with amask of a different opening corresponding to the N-well regions 20′ andan implantation process that will result in shallow N-wells 20″. Thestructure 10′″″″ of FIG. 12 is also devoid of the STI structures 16.

The method(s) as described above is used in the fabrication ofintegrated circuit chips. The resulting integrated circuit chips can bedistributed by the fabricator in raw wafer form (that is, as a singlewafer that has multiple unpackaged chips), as a bare die, or in apackaged form. In the latter case the chip is mounted in a single chippackage (such as a plastic carrier, with leads that are affixed to amotherboard or other higher level carrier) or in a multichip package(such as a ceramic carrier that has either or both surfaceinterconnections or buried interconnections). In any case the chip isthen integrated with other chips, discrete circuit elements, and/orother signal processing devices as part of either (a) an intermediateproduct, such as a motherboard, or (b) an end product. The end productcan be any product that includes integrated circuit chips, ranging fromtoys and other low-end applications to advanced computer products havinga display, a keyboard or other input device, and a central processor.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

What is claimed:
 1. A semiconductor device comprising: a plurality offin structures formed comprised of substrate material; a well of a firstconductivity type and a well of a second conductivity type formed withinthe substrate material and corresponding fin structures of the pluralityof fin structures; a source contact on an exposed portion of a first finstructure; drain contacts on exposed portions of adjacent fin structuresto the first fin structure; and a gate structure in a dielectric fillmaterial about the first fin structure and extending over the well ofthe first conductivity type, wherein: the well of the first conductivitytype is a continuous shallow N-well and the well second conductivitytype is a P-well; and the gate structure and the first fin structure arelocated completely over the shallow N-well, thereby forming a floatingcontact.
 2. The semiconductor device of claim 1, wherein the sourcecontact and the drain contacts are comprised of an epitaxial growthmaterial with an n+implantation process.
 3. The semiconductor device ofclaim 1, wherein the dielectric fill material extends between the firstfin structure and the adjacent fin structures.
 4. The semiconductordevice of claim 3, wherein the dielectric fill material overlaps aportion of an upper surface of the continuous shallow N-well.
 5. Thesemiconductor device of claim 4, wherein the dielectric fill materialoverlaps a portion of an upper surface of the P-well.
 6. Thesemiconductor device of claim 1, wherein the plurality of fin structuresincludes body contact fins.
 7. The semiconductor device of claim 1,wherein the adjacent fin structures and the drain contacts are locatedover the shallow N-type well.
 8. The semiconductor device of claim 1,wherein the adjacent fin structures and the drain contacts are floatingp-fins.
 9. A semiconductor device comprising: a center floating p-fincorresponding to a source region; fins adjacent to the center floatingp-fin corresponding to drain regions; a gate structure formed about thecenter floating p-fin; and a continuous shallow N-well region formedunder the center floating p-fin and the fins adjacent to the centerfloating p-fin.
 10. The semiconductor device of claim 9, wherein asource contact is formed on an exposed portion of the center floatingp-fin.
 11. The semiconductor device of claim 9, wherein drain contactsare formed on exposed portions of the fins adjacent to the centerfloating p-fin.
 12. The semiconductor device of claim 9, wherein thegate structure is formed in a dielectric fill material.
 13. Thesemiconductor device of claim 12, wherein the gate structure extendsover the continuous shallow N-well region.